Download Skeletal Muscle - Valhalla High School

The muscular System
• What do skeletal
muscles do?
• How do muscles
work?
Functions of Muscle Tissue
• Produce movement
– Muscle pulls tendons to move the skeleton
• Maintain posture and body position
- Continuous muscle contraction
• Support soft tissue
-Support weight of visceral organs
• Movement of substance around the body
- Encircle openings to digestive and urinary tracts: sphincters
- Regulate blood flow, movement of food, enzyme, propel urine….
• Maintain body temperature
– Energy from contraction is converted to heat
Types of muscles tissue
Muscle Tissue
Skeletal
Muscle Tissue
smooth (involuntary)
Muscle Tissue
cardiac (involuntary)
Skeletal Muscle
• Muscles are bundles of cells and fibres.
• Muscles work in a very simple way; all they do is contract or
relax.
• Muscles can only pull, they never push.
• Muscles generally work in pairs to produce movement: when
one muscle contracts the other relaxes.
• There are 630 active muscles in your body
The Properties of Muscle
Excitability
 muscles can receive and respond to a stimulus.
Extensibility
 muscles can be stretched or contracted.
Elasticity
 muscles return to their original shape after contraction.
Muscle Action
• Skeletal muscles produce movement by exerting
force on tendons, which pull bones.
• When muscle contracts it shortens and pulls two
jointed bones together.
• However the two bones do not move equally in
response to the force, one is held in place by other
muscles which brace it so that the other bone will
move towards it.
 The Agonist – is the muscle most directly involved in
any movement. (prime – mover)
 The Antagonist – is the muscle(s) of the same joint that
relaxes when the agonist is contracting or can produce
the opposite movement when it contracts.
 The Synergists – are any other muscles that aid the
prime mover (bracing a joint or adding more power when
required etc).
The o’s & i’s
• The Origin – is the attachment site of the
muscle’s tendon to the stationary bone.
• The Insertion – is the attachment site to
the moveable bone
Muscle groups
• For any movement there will be more than one muscle
involved since there will be forces created throughout the
body as a consequence of that movement.
• Muscles can only pull; so in order to reverse an action such
as flexing the elbow there must be an opposing action to
extend it again.
It is in this way that muscles are grouped in
opposition in order to produce any movement.
 Muscles which cause the movement of a joint
are connected to two different bones; muscle
contraction pulls them together.
 An example would be the contraction of the
biceps and a relaxation of the triceps. This
produces a bend at the elbow, an action called
flexion
 The contraction of the triceps and relaxation of
the biceps produces the effect of straightening
the arm.
Extension of the elbow
• Q - Which muscle needs
to contract to produce this
movement?
• A– The triceps.
• Q - Is this the agonist or
antagonist?
• A – now it’s the agonist
(prime mover)
Anatomy of Skeletal Muscles
• Muscle contractions require energy
– Blood vessels deliver oxygen and nutrients to
produce ATP
– ATP is the cellular energy molecule produce in
the mitochondria
• Muscle contractions are under stimulation from the
CNS
– Voluntary control
– Axons connect to individual muscle fibers
Anterior View
Posterior View
The muscular system
• BBC MUSCLE GAME